/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package io.druid.segment.data;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public class VSizeCompressedObjectStrategy extends CompressedObjectStrategy<ByteBuffer>
{

  private final int expectedBytes;

  public static VSizeCompressedObjectStrategy getBufferForOrder(
      final ByteOrder order,
      final CompressionStrategy compression,
      final int expectedBytes
  )
  {
    return new VSizeCompressedObjectStrategy(order, compression, expectedBytes);
  }

  protected VSizeCompressedObjectStrategy(
      ByteOrder order,
      CompressionStrategy compression,
      int expectedBytes
  )
  {
    super(order, new BufferConverter<ByteBuffer>()
    {
      @Override
      public ByteBuffer convert(ByteBuffer buf)
      {
        return buf;
      }

      @Override
      public int compare(ByteBuffer lhs, ByteBuffer rhs)
      {
        return CompressedByteBufferObjectStrategy.ORDERING.compare(lhs, rhs);
      }

      @Override
      public int sizeOf(int count)
      {
        return count; // 1 byte per element
      }

      @Override
      public ByteBuffer combine(ByteBuffer into, ByteBuffer from)
      {
        return into.put(from);
      }
    }, compression);

    this.expectedBytes = expectedBytes;
  }

  @Override
  protected ByteBuffer bufferFor(ByteBuffer val)
  {
    return ByteBuffer.allocate(expectedBytes).order(order);
  }

  @Override
  protected void decompress(ByteBuffer buffer, int numBytes, ByteBuffer buf)
  {
    decompressor.decompress(buffer, numBytes, buf, expectedBytes);
  }
}
